Monday 27 February 2012

UNIT 3 : CHEMICAL FORMULA AND EQUATIONS

Relative Mass
RAM: To state the meaning of relative mass and solve numerical problems
FMM: to state the meaning of RAM,RMM and RFM based on carbon-12 scale
RMM: to calculate RAM, RMM and RFM using the chemical formulae of various substances
  1. a single atom is too small and lightr and cannot be weighted directly.
  2. The best way to determine the mass of a single atom is to compare it mass to the mass of another atom of an element that is used as a standard.
  3. Ram has no unit. The new standard today is the carbon-12 atom, Ram based on the carbon-12 scale is the mass of one atom of the element compared with 1/12 of the mass of an atom of carbon-12.
  1. RMM / RFM is obtained by adding up the RAM of all the atoms that are present in the molecule.
Molecular substance
Molecular Formula
Relative Molecular Mass
Oxygen
O2


Water
H2O


Carbon dioxide
CO2


Ammonia
NH3


  1. For ionic substance, RMM is replace with relative formula mass(RFM)
Substance
Chemical Formula
Relative Molecular Mass
Sodium chloride
NaCl


Potassium oxide
K2O


Copper(II) sulphate
CuSO4


Ammonium carbonate
(NH4)2CO3


Aluminium nitrate

Al(NO3)3

Calcium hydroxide

Ca(OH)2

Lead(II)hydroxide

Pb(OH)2

Hydrated copper(II) sulphate

CuSO.5H2O

Mole concept
Mole and number of particles: - to solve numerical problems involving mole and the number of atoms
Mole and the mass of substances / : to solve numerical problems involving mole and the mass of
Mole and volume of gas substances, number of particles and volume of gas using mole concept.
  1. To describe the amount of atoms, ions or molecules, mole is used.
  2. A Mole is an amount of substance that contains as many particles as the number of atoms is exactly 12 g of carbon-12
  3. Amol of a substance is the amount of substance which contains a constant number of particles( Atoms, Ions,Molecules), which is 6.02 x 10 23
  4. The number of 6.02 x 10 23 is called the Avogadro constant(NA)
  5. For compunds that exist as molecule/ions, the number of atoms/ions in that compunds must be known
  6. The symbol of mole is mol.
    Number of moles and mass of substance
    1. Molar Mass:
    a) Molar mass is the mass of one mole of any substance
    b) Molar mass is the relative atomic mass, relative molecular mass and relative formula mass of a substance in gmol-1.
    c) Molar mass of any substance is numerically equal to its relative mass.
Number of moles and volume of gas.
  1. Molar volume of gas : Volume occupied by one mole of any gas is 24dm3 at room conditions and 22.4 dm3at standard temperature and pressure(STP)
  2. the molar volume of any gas is 24dm3 at room conditions and 22.4 dm3 at STP.
  3. Conclusion: One mole of any gas always occupy the same volume under the same temperature and pressure.
Chemical formula and equations
Empirical formula : to state the meaning of empirical formula and describe the laboratory activities
to determined empirical formula
Molecular formula: to solve numerical problems involving empirical formula
Chemical Formulae: to write the formulae of common cations and anions, and to write the chemical formulae for ionic compounds
Chemical Equations : to write balanced chemical equations and solve numerical problems involving mole concept
  1. Symbol of elements – use the first capital letter,
    if there is more htan one which share the same first capital letter thus it mus used together with small letters.
    Example:
    Carbon = C, Hydrogen = H
    Nitrogen= N, sodium = Na
    Sulphur = S, Silicon = Si
  1. Chemical formula is a set of chemical symbols for atoms of elements in whole numbers representing chemical substances.
Chemical substance
Chemical formula
Notes
Water
H2O
2 atoms of H combine with 1 atom of O
Ammonia
NH3
3 atoms of H combine with 1 atom of N
Propane
C3H8
3 atoms of C combine with 8 atoms of H
  1. Information that can be obtained from the chemical formula:
    a) all te element present in the compound
    b) Number of atoms of each element in the compound
    c) calculation of RMM / RFM of compound.
  2. Empirical formula = a formula that shows the simplest whole number ratio of atoms of each element in the compound
  3. Ehe formula can be determined by calculating the simplest ratio of moles of atoms of each element in the compound. EF can be obtained by experiment
    example : the empirical formula of Magnesium oxide or copper(II) oxide
  1. To calculate the empirical formula of a compound, use the following table:
Element


Mass of element(g)


Number of moles of atom


Simplest ratio of moles



Molecular Formula of a compound shows the actual number of atoms of each element that are present in a molecule of the compound

Molecular formula = ( EF ) n, where n is integer ( the repeatation of the EF )

Compound
Molecular formula
Empirical formula
Value of n
Water
H2O
H2O
1
Carbon dioxide
CO2
CO2
1
Sulphuric acid
H2SO4


Ethene
C2H4
CH2
2
Benzene
C6H6
CH

Glucose
C6H12O6


  1. Percentage composition by mass of an element in a compound
example: calculate the percentage composition by mass of nitrogen in the following compounds
[RAM: N=14, H=1, O=16, S=32, K=39]
i- (NH4)2SO4 ii- KNO3

% N = 2 x 14 x 100%        % N = 14 x 100%
           132                                101
       = 21.2%                           = 13.9%
  1. Chemical formula of an ionic compound comprising of the ions Xm+ and Yn- is by exchanging the charge on each ions. The formula obtained will be XmYn
    Example:
    Copper (ii) nitrate Zinc oxide
    Cu2+ NO3-   = Cu (NO3)2 = Cu(NO3)2        Zn2+ O2-   = Zn O = ZnO
Chemical equation
  1. a) type of chemical equation-
    i.equation in words – using names of reactants and products
    ii. equation using symbols – represented by chemical formula and symbols
    examples:
    + seperating reactants / products
    (g) gaseous
    (aq) aqueous
    (s) solid
Sign / symbols
Meaning
Sign / symbols
Meaning
    +
    seperating reactants / products
Heating/ heat energy is given
    (g)
    gaseous
Produces
    (aq)
    aqueous
precipitate
    (l)
    liquid
Gas release
    (s)
    solid

Reversible reaction


Saturday 25 February 2012

Peluang baru di tempat baru.

Alhamdulillah, sekali lagi cikgu merasa begitu terpukul dengan cubaan yang datang tanpa diundang. Masa hujung tahun lalu cikgu ada memohon pertukaran sekolah kerana dah beli rumah kat SP. Namun tanpa prasangka tidak diluluskan oleh Pihak Kementrian. Apakan daya mungkin itu yang terbaik untuk cikgu pada masa itu. Setelah terubat luka di kalbu maka cikgu pun bangun dan tetapkan sasaran baru untuk tahun ini. Sedang selesa dengan apa yang cikgu ada sekarang tiba-tiba terima pulak surat.
Jeng...Jeng..Jeng... cikgu dapat surat arahan Pertukaran dari Kementerian Pelajaran bahawa permohonan diterima... alamak... apa dah jadi ni. Masa nak tukar tak dapat tukar. Bila dah selesa kena tukar pulak. Alahai... kita hanya merancang, tapi Tuhan yang menentukan. Mungkin pada masa itu bukan sesuai untuk cikgu bertukar. Ada hikmah disebalik yang berlaku. Alhamdulillah cikgu banyak belajar untuk memaafkan dan memohon maaf. Jadi mungkin sekarang adalah masa yang terbaik untuk bertukar... Esok 26 Feb cikgu akan melapor diri di tempat baru. Doakan Cikgu ya.
Semoga kita sama2 mencapai kejayaan yang diimpikan. Walau apa pun yang terjadi, janganlah kita putus berdoa untuk mendapat rahmat dari Nya dan pohonlah bantuanNya dalam setiap yang kita lakukan, Inyaallah...
SMK Dato' Bijaya Setia.... here i come....

Thursday 9 February 2012

Lawatan Penanda Aras ke SMK Dato' Ahmad Maher, Kota Bharu

4 hingga 6 februari adalah hari yang tak terduga oleh cikgu. Dapat melawat sekolah kluster kecemerlangan yang terbilang di Kota Bharu. Bak kata pepatah, sambil menyelam, minum air. Itulah yang berlaku semasa cikgu beserta semua cikgu2 dari SMK Bukit Jambul mengadakan rombongan ke sana. Bukan hanya melawat sekolah kluster tetapi juga sempat membeli belah yang banyak sekali dalam hidup cikgu. Masakan tidak, dalam 3 hari hari tu semua tempat yang dikunjungi adalah tempat shopping. Memang peniaga sungguh orang2 Kelantan ni. Pertama sekali singgah di wakaf che yeh, pas tu, pasar siti khatijah, kemudian pengkalan kubur, diikuti pantai cahaya bulan, ke nordin batik, dan ke rantau panjang. Betulkan!... semua tempat membeli belah, namun apa yang pasti, cikgu masih mengamalkan prinsip membeli keperluan dan bukannya kehendak semata2... ditambah lagi, bukan musim mendapat rezeki terpijak lah katakan.... hehehehee.....
Jadi dibawah ni dimuatkan beberapa gambar yang sempat cikgu ambil untuk tatapan semua, cantikkan pantai cahaya bulan, namun cikgu p waktu siang tak sempat lak tgk cahaya bulan..... kena pergi sendiri di lain kali...insyaallah...
Keindahan pantai cahaya bulan

Antara babak ber'posing' dalam bas

Antara pintu kelas yang menarik perhatian

mewarna batik selepas men-chanting

Breakfast di Pasar siti khatijah

Antara acuan cop batik

Pandangan sayu meninggalkan Kelantan - sungai kelantan

Wednesday 1 February 2012

Trial PEKA for Form 4

Yesterday a session for trial PEKA was carried out in order to give a real situation for students when they sit for PEKA. Its not like an ordinary experiments when all the apparatus and materials were prepared by teacher, in PEKA experiment, the students must find their own material and apparatus and these were purposely mixed up with all apparatus and other material as well to see wheather the student know what they are doing. So lets see how form 4 Arif was doing in this trial PEKA.


At the end of this experiment, they was asked to set a graph for melting and cooling curve. Good luck you guys!

Its me...

The Life Journey Begins... Slideshow: Its’s trip from Pinang, Malaysia to 7 cities Kuala Lumpur, HCMC (near Ho Chi Minh City, Vietnam), Georgetown, Bukit Bendera (near Batu Ferringhi, Pulau Penang), Shah Alam, Jertih (near Kota Bharu, Kelantan) and Alor Setar was created by TripAdvisor. See another Malaysia slideshow. Take your travel photos and make a slideshow for free.